Visual/Spatial Properties of Posterior Parietal Neurons

描述（来自申请人的摘要）：虽然后顶骨 皮质（PPC）长期以来一直被认为是一个区域， 空间意识和空间注意力的不同感觉方式， 最近的研究指出了这一领域的一个额外的、非常重要的作用 在行动计划中。一个重要的进展是发现 PPC内意图的解剖图，具有不同的区域 专门用于不同的行为。在目标1中，我们将确定 这些领域之间的相互关系在运动规划。在 特别是，我们将研究LIP地区是否在决策中发挥执行作用， 使眼睛和肢体运动，或者如果LIP主要涉及 前者，后者为MIP区和5区。 另一个重要的进展是阐明了空间 在某些PPC皮质区的代表。这些结果导致了一个普遍的 提议在初期阶段进行调度规划， 灵长类动物的眼中心坐标，无论感官输入或 最终的电机输出。然而，许多PPC神经元的活性增加， 由眼睛、头部和肢体位置调节。目标2将研究这些PPC是否 “增益场”可能会影响眼球和手部运动的决定。 传统上认为， 从视网膜到视网膜的目标对象的转换， 身体坐标，然后减去物体位置， 身体坐标从身体坐标中的手的位置生成 肢体坐标的运动误差我们发现早期的运动计划 在PPC中的眼坐标中发生，提出了一种替代方案，其中 手以眼睛坐标表示，并从 目标在眼睛坐标中产生电机误差信号。我们将测试 目标3中的新理念。最后，在目标4中，我们将检查空间 在提供输入的听觉区域Tpt中的声音位置的表示 到PPC。这些实验旨在确定听觉的阶段 以头部为中心的听觉场被转换成 以眼为中心的听觉场类似于PPC中遇到的听觉场。

DESCRIPTION (From the Applicant's Abstract): Although the posterior parietal cortex (PPC) has long been appreciated to be an area for association of different sensory modalities for spatial awareness and for spatial attention, recent studies have pointed to an additional, and very major, role of this area in movement planning. One important advance has been the fmding that there is an anatomical map of intentions within the PPC, with different areas specialized for different behaviors. In Aim 1 we will determine the inter-relationship between some of these areas in movement planning. In particular, we will examine whether area LIP has an executive role in decision making for both eye and limb movements, or if LIP is primarily involved in the former, and areas MIP and 5 in the latter. Another important advance has been the elucidation of the spatial representations in some PPC cortical areas. These results have led to a general proposal that the early stages of movement planning are performed in eye-centered coordinates in primates, regardless of the sensory input or eventual motor output. However, the activity of many PPC neurons is gain modulated by eye, head and limb position. Aim 2 will examine whether these PPC "gain fields" may effect the decisions to make eye and hand movements. Classically it has been believed that the coordinate transformation for reaching results from the transformation of the traget object from retinal to body coordinates, and then the subtraction of the object location in body-coordinates from the location of the hand in body coordinates to generate the motor error in limb coordinates. Our finding that early movement planning occurs in eye-coordinates in PPC suggests an alternative scheme, in which the hand is represented in eye coordinates and is subtracted from the location of the target in eye coordinates to produce the motor error signal. We will test this new idea in aim 3. Lastly, in aim 4 we will examine the spatial representation of sound location in an auditory area, Tpt, that provides input to the PPC. These experiments are designed to determine the stage in auditory processing pathway where head-centered auditory fields are converted into eye-centered auditory fields similar to those encountered in the PPC.